Many portable devices, for example mobile telephones, are equipped with a display such as a glass or plastic display window for providing information to the user. Furthermore such display windows are now commonly used as touch sensitive inputs. The use of a touch sensitive input with the display has the advantage over a mechanical keypad in that the display may be configured to show a range of different inputs depending on the operating mode of the device. For example, in a first mode of operation the display may be enabled to enter a phone number by displaying a simple numeric keypad arrangement and in a second mode the display may be enabled for text input by displaying an alphanumeric display configuration such as a simulated Qwerty keyboard display arrangement.